ABSTRACT Histidine is an essential amino acid for human growth and also functions as a neurotransmitter in the central nervous system. In this study, a novel, rapid, and sensitive sensor has been developed to quantify histidine levels using copper‐doped carbon quantum dots (Cu‐CQDs) immobilized on electrospun PVDF nanofibers. Black pepper extract was used as a green and sustainable carbon precursor for the synthesis of CQDs through a one‐pot and time‐efficient microwave method. Black pepper, rich in aromatic and nitrogen‐containing compounds, not only provides an environmentally friendly alternative to conventional chemical precursors but also introduces active surface functional groups that enhance the interaction with Cu 2+ ions. This facilitates a highly selective and sensitive fluorescence‐based detection of histidine, achieving a low detection limit of 0.1 µM. Doping with Cu 2+ ions effectively quenched the intrinsic fluorescence of the CQDs. Subsequent addition of histidine restored fluorescence through selective chelation between histidine residues and surface‐bound Cu 2+ ions, forming a stable complex. Synthesized samples were characterized using X‐ray photoelectron spectroscopy, high‐resolution transmission electron microscopy, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, elemental mapping, and ultraviolet–visible spectroscopy. The fabricated sensor demonstrated excellent efficacy in detecting histidine in human serum and urine samples, yielding satisfactory recovery rates.
Rashidi et al. (2026) studied this question.